U.S. patent application number 12/030880 was filed with the patent office on 2009-05-21 for antiglare film and coating composition for making the same.
Invention is credited to Chin-Sung Chen, Je-Ting Chiu, Chang-Jian Weng.
Application Number | 20090128915 12/030880 |
Document ID | / |
Family ID | 40641650 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090128915 |
Kind Code |
A1 |
Weng; Chang-Jian ; et
al. |
May 21, 2009 |
Antiglare film and coating composition for making the same
Abstract
The present invention relates to an antiglare film, which
comprises a cured transparent resin layer and a type of transparent
hollow particles. The hollow particles are distributed in the
transparent resin layer and partially exposed therefrom. The ratio
of the inner diameter to the outer diameter of the hollow particle
is within a range of 0.1 to 0.9, and the ratio of the outer
diameter of the hollow particle to the thickness of the transparent
resin layer is within a range of 0.1 5 to 1. The hollow particle
and the transparent resin layer have different refractive indexes.
The hollow particles are partially exposed from the surface of the
transparent resin layer, leading the antiglare film to have
excellent antiglare properties.
Inventors: |
Weng; Chang-Jian; (Chiayi
City, TW) ; Chen; Chin-Sung; (Taoyuan County, TW)
; Chiu; Je-Ting; (Miaoli County, TW) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
40641650 |
Appl. No.: |
12/030880 |
Filed: |
February 14, 2008 |
Current U.S.
Class: |
359/601 ;
428/212 |
Current CPC
Class: |
Y10T 428/24942 20150115;
G02B 5/02 20130101 |
Class at
Publication: |
359/601 ;
428/212 |
International
Class: |
G02B 27/00 20060101
G02B027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2007 |
TW |
096143252 |
Claims
1. An antiglare film, comprising: a cured transparent resin layer;
and a type of transparent hollow particles, wherein, the hollow
particles are distributed in the transparent resin layer and
partially exposed from the transparent resin layer, the ratio of
the inner diameter to the outer diameter of the hollow particles is
within a range of 0.1 to 0.9, the ratio of the outer diameter of
the hollow particles to the thickness of the transparent resin
layer is within a range of 0.15 to 1, and the refractive index of
the hollow particles is different from that of the transparent
resin layer.
2. The antiglare film of claim 1, wherein the hollow particles
comprise an organic resin or an inorganic oxide.
3. The antiglare film of claim 2, wherein the hollow particles
comprise one selected from the group consisting of acrylic resins,
polystyrenes, acrylic-styrene copolymers, polycarbonates, and
inorganic silicon oxide compounds.
4. The antiglare film of claim 1, wherein the diameter of the
hollow particles is within a range of 1 to 10 micrometers.
5. The antiglare film of claim 1, wherein the hollow particles are
in a spherical shape.
6. The antiglare film of claim 1, wherein the hollow particles have
a smooth surface.
7. The antiglare film of claim 1, wherein the hollow particles have
a rough surface.
8. The antiglare film of claim 1, wherein the hollow particles have
a porous surface.
9. The antiglare film of claim 1, wherein the hollow portion of the
hollow particles comprises a gas or air or is in a vacuum.
10. The antiglare film of claim 1, wherein the cured transparent
resin layer is presented in an amount of 100 parts by weight, and
the hollow particles are presented in an amount of 0.3 to 20 parts
by weight.
11. The antiglare film of claim 1, wherein the cured transparent
resin layer comprises a UV-cured transparent resin layer.
12. The antiglare film of claim 1, wherein the cured transparent
resin layer comprises one selected from the group consisting of
polyester resins, polyether resins, acrylic acid resins, epoxy
resins, urethane resins, alkyd resins, spiro acetal resins,
polythiol-polyene resins, and polybutadiene resins, each having an
acrylic functional group.
13. A coating composition for an antiglare film, comprising: 100
parts by weight of a light curable transparent resin; 0.3 to 20
parts by weight of transparent hollow particles, wherein the ratio
of the inner diameter to the outer diameter of the hollow particles
is within a range of 0.1 to 0.9, and the refractive index of the
hollow particles is different from that of the light curable
transparent resin layer after cured; and a sufficient amount of
solvent for the hollow particles to be dispersed in the light
curable transparent resin.
14. The coating composition of claim 13, wherein the hollow
particles comprise an organic resin or an inorganic oxide.
15. The coating composition of claim 14, wherein the hollow
particles comprise one selected from the group consisting of
acrylic resins, polystyrenes, acrylic-styrene copolymers,
polycarbonates, and inorganic silicon oxide compounds.
16. The coating composition of claim 13, wherein the hollow
particles have a particle size within a range of 1 to 10
micrometers.
17. The coating composition of claim 13, wherein the hollow
particles are in a spherical shape.
18. The coating composition of claim 13, wherein the hollow
particles have a smooth surface.
19. The coating composition of claim 13, wherein the hollow
particles have a rough surface.
20. The coating composition of claim 13, wherein the hollow
particles have a porous surface.
21. The coating composition of claim 13, wherein the hollow portion
of the hollow particles comprises a gas or air or is in a
vacuum.
22. The coating composition of claim 13, wherein the light curable
transparent resin comprises a UV curable transparent resin.
23. The coating composition of claim 13, wherein the light curable
transparent resin comprises one selected from the group consisting
of polyester resins, polyether resins, acrylic acid resins, epoxy
resins, urethane resins, alkyd resins, spiro acetal resins,
polythiol-polyene resins, and polybutadiene resins, each having an
acrylic functional group.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an antiglare film and a
coating composition for making the antiglare film, which may reduce
glare and dazzling caused by light.
[0003] 2. Description of the Prior Art
[0004] Polarizing sheets are often disposed on the outermost
surface of display devices. Generally, the polarizing sheets are
mainly composed of a polyvinyl alcohol (PVA) film sandwiched
between two triacetyl cellulose (TAC) support films. The surface of
the TAC films is usually subjected to optical surface treatments,
such as, coating a hard coating, or attaching an antiglare film, or
an anti-reflecting film, for enhancing physical properties or
adding optical functions. The antiglare film is usually made by
dispersing some fine particles in a hard coating to achieve an
antiglare function, for example, light scattering.
[0005] Antiglare films, also referred to as antiglare optical
films, conventionally have a structure as shown in FIG. 1. A
conventional antiglare film 12 is usually formed through dispersing
transparent particles 14 in a transparent resin 16. The transparent
resin 16 and the transparent particles 14 having approximate
refractive indexes are mixed and then coated on a substrate 10 and
cured, to form an optical film 12. Particles in the films are
partially exposed from the surface of the film to form a rough
surface, causing light 18 to be scattered and refracted on the
surface, and thus to achieve antiglare effect. For example, as
disclosed in Japan Patent Laid-open Publication No. Hei 6-18706,
silica particles are mixed into a resin and then coated on the
surface of a transparent substrate to form a layer having concaves
and convexes thereon. An antiglare effect is attained when light
beams are diffused by the concave and convex surface. However,
there is only external light diffusion presented in such method,
and the effect from internal light diffusion is not very obvious.
Accordingly, an antiglare film having both internal diffusion
ability and external diffusion ability is developed by utilizing
different amounts of two different types of particles with
different sizes and refractive indexes. For example, in U.S. Pat.
No. 6,217,176 B1, light-transparent fine particles having two
different refractive indexes are mixed in a resin. The difference
of refractive index between the two types of light transparent fine
particles and the light transparent resin is between 0.03 and 0.2,
and the light transparent fine particles have a particle size
within a range of about 1 to 5 .mu.m.
[0006] Antiglare films can be employed on a surface, such as a
surface of a display and the like, when the surface needs to reduce
glare and dazzling, and therefore, there is still a need for an
antiglare film having a better effect.
SUMMARY OF THE INVENTION
[0007] One objective of the present invention is to provide an
antiglare film and a coating composition for making the antiglare
film. The light extinction effect and antiglare effect will be
enhanced by such antiglare film.
[0008] The antiglare film according to the present invention
comprises a cured transparent resin layer and a type of transparent
hollow particles, wherein, the hollow particles are distributed in
the transparent resin layer and partially exposed from the
transparent resin layer, the ratio of the inner diameter to the
outer diameter of the hollow particles is within a range of 0.1 to
0.9, the ratio of the outer diameter of the hollow particles to the
thickness of the transparent resin layer is within a range of 0.15
to 1, and the refractive index of the hollow particles is different
from that of the transparent resin layer.
[0009] The coating composition for an antiglare film according to
the present invention comprises 100 parts by weight of a light
curable transparent resin; from 0.3 to 20 parts by weight of
transparent hollow particles, wherein the ratio of the inner
diameter to the outer diameter of the hollow particles is within a
range of 0.1 to 0.9, and the refractive index of the hollow
particles is different from that of the light curable transparent
resin layer after cured; and a sufficient amount of solvent for the
hollow particles to be dispersed in the light curable transparent
resin.
[0010] In comparison with the conventional techniques, in the
present invention, a type of hollow particles are blended or mixed
in a transparent resin and partially exposed from the transparent
resin. The hollow particle encapsulates air or other gas, or is in
vacuum in the hollow portion, such that the hollow portion and the
shell body of the hollow particle have different refractive
indexes, to cause light beams to be multi-refracted when passing
through the hollow particles, improving the light diffusion and the
antiglare effect. Accordingly, just a relatively low amount of the
hollow particles used in the antiglare film can effectively reduce
light glare and dazzling. The antiglare film of the present
invention may be used on the surface of various displays of, for
example, computers, televisions, or automobile instruments, but not
limited thereto.
[0011] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic cross-sectional view of a conventional
antiglare film;
[0013] FIG. 2 is a schematic cross-sectional view of an antiglare
film according to the present invention;
[0014] FIG. 3 is a schematic diagram showing light beam propagation
in the antiglare film according to the present invention; and
[0015] FIG. 4 shows a data table of test results for the examples
according to the present invention and the comparative
examples.
DETAILED DESCRIPTION
[0016] The antiglare film according to the present invention
comprises a cured transparent resin layer and a type of transparent
hollow particles. FIG. 2 shows an embodiment of the antiglare film
according to the present invention. A substrate 20 is covered with
an antiglare film 22. The antiglare film 22 comprises a type of
hollow particles 24 and a resin layer 28. The hollow particles 24
are particles or particulates sized in micrometers. The hollow
particles 24 are preferably uniformly distributed, in the resin
layer 28 and partially exposed from the resin layer 28. The hollow
particles 24 are light transparent and comprise a shell body 25 and
a hollow portion 26. Accordingly, the hollow particles 24 have an
inner diameter and an outer diameter. The ratio of the inner
diameter to the outer diameter (inner diameter/outer diameter) is
within a range of 0.1 to 0.9, and preferably within a range of 0.2
to 0.85. The ratio of the outer diameter of the hollow particles 24
to the thickness of the resin layer 28 is within a range of 0.15 to
1, and preferably within a range of 0.2 to 1. If the shell body is
too thin, the shell body tends to be fragile during processing or
operation. If the shell body is too thick, the effect of
multi-refractions will be insignificant. A proper thickness will
render a better refraction result. The resin layer 28 is light
transparent. In the present invention, the refractive index of the
hollow particles is different from the refractive index of the
resin layer. The difference may be for example more than 0.02, and
preferably between 0.003 and 0.2, to cause refraction at the
interface and facilitate light diffusion.
[0017] The hollow particle in the antiglare film according to the
present invention may be also referred to as "hollow particulate".
It is spherical with a smooth, rough, or porous surface. When the
surface is porous, it is preferred that the hollow particles have a
specific surface area of 100 g/m.sup.2 or more, to favor the
dispersion in the transparent resin layer. The outer diameter of
the hollow particles may be for example from 1 to 10 .mu.m, and
preferably from 1 to 5 .mu.m. The inner diameter of the hollow
particles may be for example from 0.1 to 9 .mu.m, and preferably
from 0.15 to 4.5 .mu.m. The shell body may comprise a material of
organic resin or inorganic oxide, for example, acrylic resins,
polystyrenes, acrylic-styrene copolymers, polycarbonates, inorganic
silicon oxide compounds, and the like. The hollow portion (or
referred to as "the central portion of the hollow particle") may be
air or other gas, or in vacuum, but not particularly limited
thereto.
[0018] The transparent resin layer in the antiglare film according
to the present invention may be an ordinary hard coating, such as,
a UV light curable transparent resin layer, which preferably
comprises an acrylic functional group. The examples of the resin
layer may be preferably polyester resins, polyether resins, acrylic
acid resins, epoxy resins, urethane resins, alkyd resins, spiro
acetal resins, polythiol-polyene resins, polybutadiene resins, and
the like, which has an acrylic functional group and a low molecular
weight.
[0019] The amount of the cured transparent resin layer or the
hollow particles contained in the antiglare film of the present
invention is not particularly limited, and it is believed that as
long as there are hollow particles dispersed in the cured
transparent resin layer, the antiglare effect exhibits. In
addition, the amount of the hollow particles to be used may depend
on material species, material properties, particle size, inner and
outer diameters, and a desired haze value. The haze value probably
used for antiglare is usually within a range of about 3 to 90.
Therefore, the amount of the hollow particles may depend on the
desired haze value. Substantially, the hollow particles may be used
in an amount of from 0.3 to 20 parts by weight, more preferably
from 0.5 to 15 parts by weight, and most preferably from 1 to 10
parts by weight, based on 100 parts by weight of the cured
transparent resin layer, but not limited thereto.
[0020] The antiglare film according to the present invention can be
applied on many substrates to provide the antiglare function.
Particularly, it can be applied to highly transparent organic
substrate of, for example, TAC, polyethylene terephthalate (PET),
diacetylenecellulose, cellulose acetate butyrate, polyether
sulfone, polyacrylic resin, polyurethane resin, polyester,
polycarbonate, polysulfone, polyether, polymethyl pentene,
polyether ketone, poly(meth)acrylonitrile, or the like. The
substrate may be a film having a thickness of for example 25 .mu.m
to 300 .mu.m.
[0021] When a light is emitted onto the antiglare film according to
the present invention, some hollow particles exposed to the ambient
may scatter the light, and this causes an exterior diffusion.
Furthermore, the light entering the internal portion of the
antiglare film, including the light entering the internal portion
of the antiglare film from the ambient or from the substrate, may
be multi-refracted when it passes through the hollow particles, and
this causes interior light diffusion within the resin layer. For
example, FIG. 3 shows light beam propagation in the antiglare film
according to the present invention. The light beams 30 and 32 enter
the resin layer 28 from the substrate respectively. The light beam
30 encounters the hollow particle 24 and passes the shell body 25,
the hollow portion 26, and again the shell body 25 of the hollow
particle 24, and thus experiences multi-refractions. Finally, the
light beam 30 is scattered at a large scattering angle to diffuse
into the ambient environment. The light beam 32 does not encounter
the hollow particle 24, but directly passes through the resin layer
28, and then is refracted into the ambient environment. The light
beam 31 enters the hollow particle 24 from the ambient environment
and is reflected with different reflection angles at the interface
between the hollow particle and the ambient environment and at the
interface within the hollow particle. Therefore, utilizing the
hollow particles in the antiglare film according to the present
invention offers the exterior light diffusion effect as well as the
interior light diffusion effect. In addition, to achieve a good
antiglare effect, only a small amount of the hollow particles is
needed.
[0022] The antiglare film according to the present invention may be
attached to a substrate in a form of a cured film to achieve the
antiglare effect, or may be formed on the substrate through coating
and curing a pre-made coating liquid on the substrate to achieve
the antiglare effect. Such pre-made coating liquid herein is the
coating composition for making the antiglare film according to the
present invention, which is a mixture and comprises an aforesaid
light curable transparent resin, a type of aforesaid transparent
hollow particles, and a solvent.
[0023] Similar to the description mentioned above, the amounts of
the transparent hollow particles and the light curable transparent
resin may depend on material species, material properties, particle
size, inner and outer diameters, and the desired haze value. Among
these, it is preferred that an amount of 0.3 to 20 parts by weight,
more preferably 0.5 to 15 parts by weight, and most preferably 1 to
10 parts by weight of transparent hollow particles is used based on
100 parts by weight of the light curable transparent resin. It is
preferred that the solvent is used in a sufficient amount to allow
the hollow particles to be dispersed in the light curable
transparent resin, and preferably allow the whole coating
composition to have a viscosity of 5 to 100 CPS, in view of the
convenience for coating operation. After the coating composition is
coated on the substrate and the transparent resin is cured by
irradiation, a cured transparent resin layer as described above is
obtained. The solvent is preferably volatile, such that it can be
removed through volatilization during the coating and the curing
processes. The useful solvent may be, for example, methyl ethyl
ketone (MEK), toluene, ethyl acetate, or the like.
[0024] Some examples are described hereinafter to detail the
fabrication of the antiglare film according to the present
invention and compared with comparative examples.
EXAMPLE
Example 1
[0025] 100 parts by weight of UV curable resin was diluted in MEK
solvent to form a coating solution with a solid content of about
80%, and 3 parts by weight of silicon dioxide hollow particles with
an average particle size of about 3.5 .mu.m was added and stirred
to disperse in the UV curable resin, thereby obtaining an antiglare
coating solution with a viscosity of 14-18CPS. The coating solution
was applied on an 80 .mu.m-thick TAC transparent substrate, and the
resultant was placed in an 80.degree. C. air circulating oven to
dry for about 1 minute. Thereafter, the resultant was irradiated
with a UV light having a dose of 540 mJ/cm.sup.2, to form an
antiglare film of the present invention.
Example 2
[0026] 100 parts by weight of UV curable resin was diluted in MEK
solvent to form a coating solution with a solid content of about
80%, and 2 parts by weight of acrylic hollow particles with an
average particle size of from about 7 to 8 .mu.m was added and
stirred to disperse in the UV curable resin, thereby obtaining an
antiglare coating solution with a viscosity of 14-18CPS. The
coating solution was applied on an 80 .mu.m-thick TAC transparent
substrate, and then the resultant is placed in an 80.degree. C. air
circulating oven to dry for about 1 minute. Thereafter, the
resultant was irradiated with an UV light having a dose of 540
mJ/cm.sup.2, to form an antiglare film of the present
invention.
Comparative Example 1
[0027] 100 parts by weight of UV curable resin was diluted in MEK
solvent to form a coating solution with a solid content of about
65%, and 3 parts by weight of inorganic silicon oxide particles
with an average particle size of about 5 .mu.m and a refractive
index of 1.48 was added and stirred to disperse in the UV curable
resin. The resultant coating solution was applied on an 80
.mu.m-thick TAC transparent substrate, and then placed in an
80.degree. C. air circulating oven to dry for about 1 minute.
Thereafter, the resultant was irradiated with a UV light in a dose
of 540 mJ/cm.sup.2, to form an antiglare film.
Comparative Example 2
[0028] 100 parts by weight of UV curable resin was diluted in MEK
solvent to form a coating solution with a solid content of about
65%, and 3 parts by weight of organic acrylic particles with an
average particle size of about 5 .mu.m and a refractive index of
1.49 was added and stirred to disperse in the above resin. The
resultant coating solution was applied on an 80 .mu.m-thick TAC
transparent substrate, and then placed in an 80.degree. C. air
circulating oven to dry for about 1 minute. Thereafter, the
resultant was irradiated with a UV light in a dose of 540
mJ/cm.sup.2, to form an antiglare film.
[0029] The test results of the antiglare films made from Examples 1
and 2 and Comparative Examples 1 and 2 are listed in the data table
shown in FIG. 4. The haze value was tested in accordance with the
method specified in JIS K 7105, the gloss was tested in accordance
with the method specified in JIS Z 8741, and the hardness was
tested in accordance with the method specified in JIS K 5600. It is
known from the results shown in the data table that the haze value
of the antiglare film using hollow particles is superior to the
haze value of the antiglare film using solid particles as antiglare
particulates. As shown by Examples 1 and 2, either the silicon
dioxide hollow particles or the acrylic hollow particles are used
as antiglare particulates, the optical performance of the resultant
films is superior to those using the solid particles as antiglare
particulates in Comparative Examples 1 and 2. In a condition that
the different particles are used in a same amount, the antiglare
film of the present invention not only has an increased haze value,
but also has an increased internal haze value due to interior
multi-refraction and diffusion. Furthermore, the gloss is reduced
due to the reduction of the surface reflection caused by partially
exposed particles. Accordingly, the antiglare effect of the
transparent material is truly enhanced by adding the hollow
particles. In addition, with respect to the porous hollow
particles, the greater surface area, the better dispersion thereof
in the resin.
[0030] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention.
* * * * *